We study the importance of discretion in antitrust enforcement by analyzing the response of asset prices to the sudden … accession of Theodore Roosevelt to the presidency. During McKinley's term in office the largest wave of merger activity in … American history occurred, and his administration did not attempt to use antitrust laws to restrain any of those mergers. His …

In this article, I explain the inadequacy of our current state of knowledge regarding the effectiveness of antitrust … the effectiveness of antitrust policy. There are two types of data one requires in order to perform such an analysis. One … is data on the relevant market pre and post merger. The second is data on the specific predictions of the government …

In this paper we review issues relating to antitrust and competition in health care markets. The paper begins with a … brief review of antitrust legislation. We then discuss whether and how health care is different from other industries in … ways that might affect the optimality of competition. The paper then focuses on the main areas in which antitrust has been …

The challenge of effective merger enforcement is tremendous. U.S. antitrust agencies must, by statute, quickly forecast … empirical basis for antitrust enforcement, and provides guidance on the key measurement issues researchers confront in … estimating the price effects of mergers. We also describe how evidence from merger retrospectives can be used to evaluate the …

Antitrust authorities search public documents to discover anticompetitive mergers. Thus, investor disclosures may alert … disclosure thresholds stipulated by securities law. We find that releasing information to investors poses antitrust risk. Second …, we present a method for measuring undisclosed merger activity that relies on financial accounting reporting requirements …

We study optimal merger policy in a dynamic model in which the presence of scale economies implies that firms can … computationally, allows firms to invest or propose mergers according to the relative profitability of these strategies. An antitrust … authority is able to block mergers at some cost. We examine the optimal policy when the antitrust authority can commit to a …

We analyze the optimal dynamic policy of an antitrust authority towards horizontal mergers when merger proposals are … endogenous and occur over time. Approving a currently proposed merger will affect the profitability and welfare effects of … potential future mergers, the characteristics of which may not yet be known to the antitrust authority. We show that, in many …

Concentration-based screens for horizontal mergers, such as those employed in the US DOJ and FTC Horizontal Merger … Guidelines, play a central role in merger analysis. However, the basis for these screens, in both form and level, remains unclear …

Sunk costs play a central role in antitrust economics, but are often misunderstood and mismeasured. I will try to … clarify some of the conceptual and empirical issues related to sunk costs, and explain their implications for antitrust … just as relevant for antitrust analysis as the direct cost of a machine or a factory …